Evaluation of a diode laser-assisted vacuum-type charged droplet beam source

The electrospray droplet impact (EDI) method based on ambient electrospray technique was developed as a novel massive cluster beam gun, but in its current status, the EDI method lacks adequate beam focusing and brightness. To improve the performance of the current EDI method, we developed a technique for producing electrospray of aqueous solutions under vacuum. In a previous study, the tip of the electrospray emitter was irradiated with an infrared (IR) CO2 laser (wavelength: 10.6 mu m) to prevent freezing of the aqueous solutions. In this paper, a near-IR diode laser (wavelength: 808nm) was adopted for heating the tip of the electrospray emitter as an alternative to the IR laser. A stable vacuum electrospray of aqueous solutions was obtained, whereas the 808nm light was poorly absorbed by water compared with the 10.6-mu m IR laser. The characteristics of the vacuum electrospray assisted by a near-IR laser are presented. Copyright (c) 2014 John Wiley & Sons, Ltd.